The emerging landscape of circular RNA in life processes

Abstract

Circular RNAs (circRNAs) are a novel class of non-coding RNA that assumes a covalently closed continuous conformation. CircRNAs were previously thought to be the byproducts of splicing errors caused by low abundance and the technological limitations. With the recent development of high-throughput sequencing technology, numerous circRNAs have been discovered in many species. Recent studies have revealed that circRNAs are stable and widely expressed, and often exhibit cell type-specific or tissue-specific expression. Most circRNAs can be generated from exons, introns, or both. Remarkably, emerging evidence indicates that some circRNAs can serve as microRNA (miRNA) sponges, regulate transcription or splicing, and can interact with RNA binding proteins (RBPs). Moreover, circRNAs have been reported to play essential roles in myriad life processes, such as aging, insulin secretion, tissue development, atherosclerotic vascular disease risk, cardiac hypertrophy and cancer. Although circRNAs are ancient molecules, they represent a newly appreciated form of noncoding RNA and as such have great potential implications in clinical and research fields. Here, we review the current understanding of circRNA classification, function and significance in physiological and pathological processes. We believe that future research will increase our understanding of the regulation and function of these novel molecules.

Salivary Circular RNAs Hsa_Circ_0001874 and Hsa_Circ_0001971 as Novel Biomarkers for the Diagnosis of Oral Squamous Cell Carcinoma

“…There is increasing evidence that circRNAs play important roles in the regulation of gene expression at the posttranscriptional level [5][6][7]. Accordingly, it has been demonstrated that many circRNAs serve as competing endogenous RNAs to bind with microRNAs (miRNAs) and inhibit the activity and function of the targeted miRNAs [8,9].…”

Circular RNA Expression Profile and Analysis of Their Potential Function in Psoriasis

“…Remarkably, emerging evidence indicates that some circRNAs can serve as competitive endogenous RNA (ceRNA) of microRNA (miRNA) through its miRNA response elements (MREs), which can competitively binding miRNAs to release or attenuate translational repression or degradation through sequestering miRNAs away from parental mRNA [15,16]. Moreover, circRNAs have been reported to play essential roles in many life processes, such as aging, insulin secretion, tissue development, atherosclerotic vascular disease risk, cardiac hypertrophy, and cancer [17]. Importantly, some circRNAs were involved in regulating immunity, inflammation, and cell proliferation in many types of cells [18][19][20].…”

Expression Profiling Identifies Circular RNA Signature in Hepatoblastoma

“…circRNAs could act as miRNA sponges, and regulate the availability of miRNA for binding mRNAs [19]. We thus determined whether circ_0015756 acted as a miRNA sponge.…”